• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.1795-1804
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• 2014

Owing to the reduction in the peak power of a DC railway subsystem, many studies on energy storage system (ESS) applications have received attention. Each application focuses on improving the efficiency and addressing regulation issues by utilizing the huge regenerative energy generated by braking-phase vehicles. The ESS applications are widely divided into installation on a vehicle or in a substation, depending on the target system characteristics. As the main purpose of the ESS application is to reduce the peak power of starting-phase vehicles, an optimized ESS utilization can be achieved by the operating at the highest peak power section. However, the weight of an entire vehicle, including those of the passengers, continuously changes during operation; thus, considering the total power consumption and the discharging point is difficult. As a contribution to the various storage device algorithms, this study deals with ESS on board vehicles and introduces an ESS operating plan for peak-power reduction by investigating the weight of a train on a real-time basis. This process is performed using a train-performance simulator, and the simulation accuracy can be increased because the weight in each phase can be adopted in the simulation.

• Tribology and Lubricants
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• v.31 no.2
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• pp.42-49
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• 2015

Because of the growing need for high-speed transport options such as trains and aircraft, there is increasing demand for technology related to high-speed trains. Among them, braking systems are important in high-speed trains in terms of reliability. Especially, the disk brake system, in use in most high-speed trains, transforms kinetic energy into thermal energy and noise. Therefore, the material properties of both the friction materials and disks are expected to influence the tribological characteristics. In this paper, the tribological characteristics depend on the hardness of the brake disks between the Cu-based sintered metallic friction material and the heat-treated heat-resisting steel disks. A lab-scale dynamometer used to perform braking tests at a variety of braking speeds using dry conditions. The test results revealed that the hardness of the disks affects the friction coefficients, friction stabilities, and wear rates. Thus, the brake system using the heat-resisting steel disk requires proper heat-treatment. These differences are considered to be caused by the change in tribological mechanisms and the generation of an oxide layer on the friction surfaces. The oxide layers on the friction surfaces are confirmed to Fe₂O₃ by x-ray diffraction (XRD) and scanning electron microscope-energy dispersive spectroscopy (SEM-EDS) analysis.

• Journal of Advanced Navigation Technology
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• v.17 no.5
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• pp.524-544
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• 2013

In this paper, A tow system of miniature establishes each motor to individual 1C1M methods to control for a permanent magnet synchronous motors (PMSM) is constructed. You assume that is wiring having had the ability that can all absorb regenerative power which occurred when permanent magnet synchronous motors(PMSM) brake is all used to it, and to occur about agreement use scope expansion my electricity. To regenerative braking power securities of a PMSM and to stop of the bronzes my a control security, and that the electricity as you apply to vector control method and an speed sensor of controller to microprocessor, And you studied to speed, motor electricity energy control method to the algorithm and you brake a revival by regenerative braking power securities of a permanent magnet synchronous motors. It is proposed that motor control method to the algorithm you brake a revival by electricity braking power securities, you do to simulations regarding a momentum load and experiment.

• Tribology and Lubricants
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• v.25 no.6
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• pp.421-426
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• 2009

The brake system is important part of automobile safety system. The disc brake system is divided two parts: the rotating axisymmetrical disc and the stationary pads. During braking, the kinetic energy and potential energy of moving vehicle were converted into the thermal energy through frictional heat between the brake disc and the pads. The frictional heat, which is generated on the interface of the disc and pads, can cause high temperature during the braking process. The object of present work is to determine temperature and thermal stress, to compare to simulation results and experimental results in the disc by partial 3D model of ventilated disc brake with appropriate boundary conditions. In the simulation process, the mechanical loads were applied to the thermo-mechanical coupling analysis in order to simulate the process of heat produced by friction.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.320-325
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• 2005

Power of fuel cell tram is supplied by only fuel cell system or hybrid system of fuel cell and battery/super capacity. Fuel cell is operated by hydrogen, which is fed directly from hydrogen tank or by reforming gasoline or methanol into hydrogen. Power system is preferred with hybrid of fuel cell and battery/super capacity since it improves total energy efficiency through interaction of hybrid components and restores energy regenerated by braking. Also, power supply system by fuel cell hybrid should be designed to output optimum energy efficiency depending on driving mode of fuel cell tram.

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.717-722
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• 2007

Most of DC 1500V electric railway substations have adopted diode rectifiers to supply stable DC power. However, the diode rectifiers operate in the first quadrant of the voltage-current plane and thus need regenerative inverters which transfer the surplus regenerative power caused by regenerative braking of electric train sets into the grid. In order to select the proper capacity and installation position of regenerative inverter, it needs to investigate the consumed and regenerative energy of the electric traction substations in advance. This paper presents an analysis of regenerative energy in two substations operating in Seoul Seolleung and Kwangju Yangdong substations. DC line voltage and feeder currents are measured for a day to calculate consumed and regenerative power far four feeders. We calculated an amount of regenerative energy consumed in other feeders and estimated the cost reduction in energy consumption due to the reuse of regenerative energy

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.3
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• pp.35-40
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• 2005

In the present study, the influence of operating conditions on fuel economy for hybrid electric vehicle was analyzed. In order to accomplish this, vehicle speed, engine speed, battery current and voltage, SOC (state of charge),motor speed and torque, generator speed and torque, engine coolant temperature etc. were measured in real time. The tests were carried out under different driving cycles which are urban and highway cycles, KOREA CITY cycle and on-road driving, and also under various operating conditions such as different initial SOC, with or without regenerative braking etc.. Generally, conventional gasoline engines show a poor fuel economy at stop and go driving, because braking energy is wasted and the engine is operated in low thermal efficiency regions. However, in case of hybrid vehicles, higher fuel economy can be obtained because of utilizing the maximum thermal efficiency regions of engine, idling stop of engine, and regenerative braking etc..

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.169-176
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• 2002

Axial crushing behavior of cylindrical shell Is utilized in the braking of the high-velocity impacting object. In this paper, truncated cone shape brake device is introduced. That is, thickness of the shell is increased gradually from the impacting end to the other end. A detailed experimental investigation on the quasi-static axial crushing behavior of truncated cone type brake devices has been performed. Specimens of various shape were tested to check the influence of design parameters such as length, radius, mean thickness, and conical angle of cylinder. Influence of the material properties were also investigated by adopting aluminum, low carbon steel, and stainless steel as constructing materials. By analyzing deformation procedures of the specimens, it is seen that conical angle influence the deformation mode and the sequence of the wrinkles generation. Braking distance and mean braking force of each specimen were predicted based on the crushing load measured from the tests.

• Journal of the Korea Safety Management & Science
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• v.20 no.2
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• pp.1-8
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• 2018

This study aims to provide a real-time information to the driver by effectively operating the advanced safety device attached to the freight vehicle, thereby minimizing insecure behavior of the driver such as speeding, rapid acceleration, sudden braking, And improve driving habits to prevent accidents and save energy. Advanced safety equipment is a device that warns the driver that the vehicle leaves the driving lane regardless of the intention of the driver and reduces the risk of traffic accidents by mitigating or avoiding collision by detecting a frontal collision during driving.The main contents of this report are as follows: In case of installing a warning device on a lane departing vehicle (excluding a light vehicle) and a lorry or special vehicle with a total weight exceeding 3.5 tonnes, the driver must continue to operate unless the driver releases the function.In addition, when the automatic emergency braking system is installed, the structure should be such that the braking device is operated automatically after warning the driver when the risk of collision with the running or stopped vehicle in the same direction is detected in front of the driving lane.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.9
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• pp.1492-1498
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• 2003

This study proposes a new conceptual Hybrid Electric Brake System (HEBS) which overcomes problems of a conventional hydraulic brake system. HEBS adopt a contactless type bake system when a vehicle speed is high, to obtain superior braking performances by eddy current. On the contrary, when a vehicle speed is low, HEBS employs a contact type brake system such as conventional hydraulic brake system to generate higher brake force. Therefore, HEBS transfers faster the braking intention of drivers and guarantees the safety of drivers. Braking torque analysis is performed by using a mathematical model which is proposed to investigate the characteristic of a vehicle dynamics when the brake torque is applied. Optimal torque control is achieved by maintaining a desired slip corresponding to the road condition. The results show that HEBS reduces the stopping distance, saves the electric energy, and increases the stability.